Engine controllers for diesel engines typically determine the amount of fuel injected to the combustion chambers of the engine as a function of the average absolute air pressure existing in the engine manifold. The average absolute air pressure is typically generated by an air pressure sensor, often referred to as a MAP (Manifold Absolute Pressure) sensor, which is positioned in the intake manifold and which generates a signal indicative of the average absolute air pressure existing in the intake manifold.
If the MAP sensor fails, certain engine controllers utilize a default MAP value for continued operation until the MAP sensor can be replaced. Utilizing a default value however provides less than optimum performance and emissions control because a default value which is indicative of low MAP value can result in reduced power, while a default value which is indicative of high MAP can result in increased emissions.
Accordingly, there is a need for an engine controller which can provide improved power and reduced emissions in the event of a MAP sensor failure.